A conventional high voltage transformer includes a magnetic core, a high voltage transforming part provided with a low voltage bobbin and a high voltage bobbin surrounding the magnetic core, a rectifying part for rectifying a high voltage current induced in the high voltage bobbin and then smoothing the rectified high voltage current, and a high voltage switch part. One of the points to be duly considered in fabricating the high voltage transformer is how to electrically insulate the components of the high voltage transformer with a view to reduce the volume and fabrication costs thereof.
One typical method of electrically insulating the components of the high voltage transformer is to arrange all the components within a transformer housing and then to fill the transformer housing with an insulating material. Examples of the insulating material used for this purpose include gaseous insulating materials, such as an air, oxygen, nitrogen, and hydrogen and liquid insulating materials, such as petroleum-based insulating oil, silicon oil and chlorinated oil.
Another typical method of electrically insulating the components of the high voltage transformer is to insert insulating bodies made of, e.g., plastics or glass, into between the components of the high voltage transformer.
Even if the components of the high voltage transformer are electrically insulated by filling the insulating material or inserting the insulating bodies as noted above, it is impossible to completely eliminate the stray capacitance generated between the components of the high voltage transformer. For this reason, the components of the high voltage transformer need to be arranged in a spaced-apart relationship in order to perfectly eliminate the stray capacitance.
The spacing between the components of the high voltage transformer varies with the magnitude of the voltage applied to the respective components. This means that the respective components should be spaced apart by a distance corresponding to the magnitude of the voltage applied thereto. Such an increase in the distance between the components of the high voltage transformer leads to an increased size and weight of the high voltage transformer, thereby making the transformer costly to fabricate.